1. Field of the Invention
This invention relates to connectors for rechargeable and non-rechargeable batteries and, more particularly, to an universal connector which inherently permits product energization from both types of batteries while connecting only a rechargeable battery to a battery charging circuit.
2. Description of the Prior Art
In existing products, if rechargeable batteries are to be used for product energization during power failures, a trickle charge must be provided to keep the batteries charged while not in use. Due to the expense of rechargeable batteries and the wide availability of non-rechargeable batteries, users often desire to use non-rechargeable batteries, intentionally forgoing the advantages of rechargeable batteries. If this is to be permitted, it is essential for safety reasons that means be provided to prevent attempted charging of the non-rechargeable battery. One way to assure that charging current will not be supplied to a non-rechargeable battery is to provide in a single product separate connectors for rechargeable and non-rechargeable batteries. These connectors take advantage of unique physical configurations of the batteries to assure that the connector for rechargeable batteries cannot be inadvertantly connected to a non-rechargeable battery. For example, a typical 9-volt rechargeable battery has a recess provided between its terminals while a similar non-rechargeable battery does not have such a recess. The connector intended for use with a 9-volt rechargeable battery may be provided with a projection for entering the recess when the connector is attached to the terminals of the rechargeable battery. If an attempt is made to attach the connector to the terminals of a non-rechargeable battery, the solid wall between the battery terminals and the projection will contact each other and prevent engagement of the terminals of the connector with the terminals of the battery. An additional connector not having the projection is provided for connection to non-rechargeable batteries. While this approach assures that a non-rechargeable battery will not be inadvertently supplied with charging current, it is not entirely satisfactory in that it can confuse the user as to which connector to use with the different types of batteries and increase the product cost due to duplication of connectors and the necessity of a blocking diode to prevent attempted charging of the non-rechargeable battery. Moreover, this approach permits rechargeable batteries to be mistakenly connected to the non-charging connector in spite of clear instructions and warning labels. While this type of improper attachment does not represent a safety risk, it can lead to dissatisfaction on the part of the user because the rechargeable batteries will not thereafter be maintained in the charged condition he expects. As a result, the product will probably not work in the event of a power failure, and the unhappy user will be likely to think incorrectly that the product has failed to work properly.